Cisneros, in U.S. Pat. No. 5,308,553, the entire contents of which are hereby incorporated by reference, discloses metal hydride compounds comprising a mixture of at least one metal selected from the group consisting of silicon, aluminum, tin, and zinc; an alkali metal hydroxide; and water. These compounds have heretofore been used for separating coal fines from coal fine waste slurries, cleaning and desludging hydrocarbon storage tanks, providing fire-retardant properties to composite materials, and protecting metal parts from corrosion.
Crude oil can be easily separated into its principal products, i.e. gasoline, distillate fuels, and residual fuels, by simple distillation. However, neither the amounts nor quality of these natural products matches demand. The refining industry has devoted considerable research and engineering effort as well as financial resources to convert naturally occurring molecules into acceptable fuels. There is a real need to meet the tremendous demand for gasoline without overproducing other petroleum products for which there is less demand. As the price of crude oil increases, it is even more critical to be able to produce the highest value products from the crude oil.
Catalytic cracking is the primary refinery process for changing the molecular structure of the crude oil. The principal class of reactions in the fluidized bed catalytic cracking process, the one most commonly used, converts high boiling, low octane normal paraffins to lower boiling, higher octane olefins, naphthenes (cycloparaffins), and aromatics. However, naphtha converted by fluidized bed catalytic cracking may contain unacceptably high amounts of foul smelling mercaptans, and its thermal stability may be too low for it to be economically useful.
Catalytic reforming can also be used to increase the octane of gasoline components. The feed is usually naphtha boiling in the 80-210° C. range, and the catalysts used are platinum on alumina, normally with small amounts of other metals such as rhenium. Depending upon the catalysts and operating conditions, the following types of reactions occur to a greater or lesser extent:
1. Heavy paraffins lose hydrogen and form aromatic rings;
2. Cycloparaffins lose hydrogen to form corresponding aromatics;
3. Straight-chain paraffins rearrange to form isomers and
4. Heavy paraffins are hydrocracked to form lighter paraffins.
Reforming generates highly aromatic, high octane product streams and much hydrogen. The hydrogen, which can be used to improve the quality of many other refiner streams, is an extremely valuable product of reforming. However, reforming also produces benzene, polynuclear or multiring aromatics, and light gas (one to four carbon atoms). Benzene is a recognized carcinogen and its concentration in gasoline is regulated in the United States. Polynuclear aromatics can contribute to deposits in the combustion chamber of automobiles; these compounds can be removed by distilling the entire reformate and discarding the heaviest fractions.
Hydroprocessing or hydrotreatment to remove undesirable components from hydrocarbon feed streams catalytically is well know to increase the commercial value of heavy hydrocarbons. However, “heavy” hydrocarbons liquid streams, and particularly reduced crude oils, petroleum residua, tar, sand bitumen, shale oil or liquid coal or reclaimed oil, generally contain contaminants such as sulfur and/or nitrogen which deactivate catalyst particles during contact by the feed stream and hydrogen under hydroprocessing conditions. Hydroprocessing conditions are normally in the range of 212° F. to 1200° F. at pressures of from 20 to 300 atmospheres.
Since 1990, the Clean Air Act Amendment has mandated reformulation of gasoline and diesel fuel to achieve specific reductions in emissions of volatile organic compounds, toxic compounds, and carbon monoxide without increasing emissions of nitrogen oxides. Gasoline must be reformulated to have lower vapor pressure and benzene content, as well as lower total aromatics of about less than 25%, depending upon the benzene content. There are also baselines for olefins, sulfur, and 90% distillation point. Diesel fuel specifications were changed to specify a maximum of 0.05% sulfur and a minimum cetane index of 40, or a maximum aromatics content of 35% vol for on-road diesel. For off-road diesel, higher sulfur concentrations are permitted.
MTBE, methyl tertiary butyl ether, is the most widely used ingredient in reformulated gasoline. In 1999 the United States produced 4.5 billion gallons of MTBE. A gallon of gasoline contains 10% MBTE. Unfortunately, MTBE does not break down easily, and is more soluble in water than any other ingredient in gasoline. MTBE, even at low levels, gives water a turpentine odor and taste, and is now considered to be a possible carcinogen. MTBE has been found contaminating ground and surface water in all fifty states. The cost to clean up just one city in Southern California has been estimated at $100,000,000.00. The federal government has declared that MTBE will be banned by 2003 because of environmental problems and possible risks to humans.
There is a real need for a method for producing gasoline and diesel fuels that will reduce harmful emissions and retain fuel economy.
Additionally, changes in market conditions and plant operating economics require examination of traditional processes and operating procedures for petroleum products and natural gas treating applications for upgrading to more stringent standards of efficiency in order to remain competitive, while returning a satisfactory operating profit margin to the company.
A typical petroleum refinery has acid gas treating requirements for several streams, including at least one of the following:                Recovered gas to fuel produced as crude oil feed is upgraded to lighter liquid products        Ethylene concentrate prepared for feedstock        Gasoline concentrate prepared for petrochemical feedstock        Liquid LPG streams (i.e., propane, ethane, butane, etc.)        Recycle hydrogen and hydrogen desulfurizing processes        Hydrogen production for hydrocracking        Sulfur recovery unit tail gas treating        Sour water treating.        
Unfortunately, the requirements for treating the above streams vary considerably. While specific solvents might be chosen for optimum treatment of each stream, in order to minimize cost, the typical refinery usually treats several streams with one solvent.
The choice of solvent may be based on individual expenses, trouble-free performance, treated product specifications, or the expectation that the overall performance will be favorable, there being more positive benefits in one solvent than liabilities. Monoethanolamine (MEA) and diethanolamine (DEA) are the more traditional solvents used in typical refinery main system acid gas removal processes.
MEA has a number of advantages as a solvent for use in refineries, including a capability of producing the lowest levels of hydrogen sulfide and carbon dioxide in the product. MEA can be partially reclaimed in the event of thermal degradation or buildup of heat stable salts. Moreover, MEA can hydrolyze carbonyl sulfide for removal. Unfortunately, MEA has high heats of reaction with hydrogen sulfide and carbon dioxide. MEA lacks selectivity, and for applications where this is a preference, energy requirements are further increased. MEA is appreciably soluble in liquid hydrocarbon streams. The potential for corrosion limits solution strength to about 15 percent. Moreover, a portion of the carbonyl sulfide and carbon dioxide removed reacts irreversibly with the MEA.
DEA can be used as a replacement for MEA. DEA has the advantage of lower heats of reaction with hydrogen sulfide and carbon dioxide, and a slight selectivity for hydrogen sulfide over carbon dioxide. DEA is six to eight times less soluble than MEA in liquid hydrocarbons, and can remove carbonyl sulfide in some cases to acceptable levels. However, DEA has insufficient selectivity for tail gas treating. Reclaiming DEA is not an easy, straightforward process, and DEA forms irreversible products with carbon dioxide. DEA does not produce treated gas specifications as low as does MEA, and the corrosion potential of DEA limits the solution strength to about 30 percent.
Polychlorinated biphenyls, or PCBs, are a family of man-made compounds having two six-membered aromatic rings with varying degrees of chlorination on the rings that comprise over 200 individual compounds which have varying degrees of toxicity and which have different physical and chemical characteristics. PCBs have been widely used in industry since the beginning of the twentieth century. PCBs exist mainly in either a liquid state or a solid state. In the liquid state, PCBs are oily liquids which are light yellow. In the solid state, PCBs are white powder.
Unfortunately, many of the characteristics which make PCBs ideal for use in industry are the characteristics which are responsible for their toxic effect on the environment. Specifically, their thermal stability, inertness, low water solubility, and low electrical conductance, made PCBs the perfect choice for use in flame retardants, electrical insulators, lubricants, and liquid seals. However, the non-reactivity and stability of the PCBs means that they accumulate in the environment and are difficult to break down.
Because of evidence that PCBs accumulate in the environment and may cause health hazards for humans and other animals, the manufacture of PCBs has been banned since 1977. Among the adverse health effects are liver damage, skin irritations, reproductive and development effects, and cancer.
There are currently four standard treatment/disposal procedures for PCBs: incineration, low temperature desorption and subsequent disposal of hazardous PCBs, biotreatment, and long term specialized storage. While each of these procedures is somewhat effective, none is free from objections and criticism. Therefore, both industry and environmental regulators are seeking new technologies to use in place of the standard procedures.
Sludges or tank bottoms are a mixture of hydrocarbons, mixed or contaminated with water and sediment. Sludges are found in different areas of the oil industry, such as in storage tanks in refineries and in production fields. Some countries have open pits where crude has been stored over the years because oil production outpaced refinery capabilities.
Ocean going tankers provide another supply of tank bottoms that must be cleaned prior to receiving new shipments of crude, or before carrying finished products. The treatment of tank bottoms may vary, but there are currently three basic methods:
(1) Mechanical methods use robots or personnel to operate equipment inside of the tank to remove both asphaltic and paraffinic bottoms. Excessive project costs are realized with mechanical methods because of the amount of time it takes to complete the cleaning, dispose of the removed product, hazardous working conditions, and increased probability of equipment damage and failure.
(2) Thermal methods are best used for tank bottoms in which the concentration of paraffins is relatively high. These methods consists of steaming, hot oiling, and attaching heaters to the tanks. Increasing the heat within the tank will melt the paraffin and temporarily convert it into a liquid. Solidification will reoccur once temperatures are lowered. At such time the paraffins are often more difficult to remove because the light end hydrocarbons have been removed. Heat only temporarily changes the paraffinic state. The desired transferable liquid state will not be maintained once the heat source is removed. It is costly to retain the heat, and there is also some residue that remains that must be cleaned by mechanical means.
(3) Chemical methods offer many advantages that are efficient, economical, and environmentally appearing. A chemical tank bottom treatment breaks up and removes the sludges while reclaiming the hydrocarbon content. This method is often less expensive when the commercially valuable hydrocarbons are converted from solid deposits into salable product to be sent to the refinery, rather than merely disposing of them by an approved method.
Materials and parts degreasing is an integral part of many industrial processes, including the manufacturing of automobiles, electronics, furniture, appliances, jewelry, and plumbing fixtures. Degreasing is also frequently used in the textile, paper, plastics, and glass manufacturing industries. It is most often used as a surface preparation process to remove contaminants and prepare raw materials and parts for subsequent operations like machining, painting, electroplating, inspection, and packaging.
The conventional manner of degreasing these parts or materials is to use solvents and mixtures of solvents, which are generally halogenated and nonhalogenated organic chemicals. Although these compounds are effective at degreasing, most are carcinogenic, according to the EPA. These chemicals create other health threats as well, including depletion of the ozone layer. Because the Environmental Protection Agency has deemed these chemicals to be hazardous, it is important to find a substitute that is environmentally safe.
Another type of hard surface cleaning is that used in food processing manufacturing lines, such as plants where meat is cooked and processed, or where nuts are shelled, roasted, and packaged. Solvent cleaning, acid cleaning, or harsh alkaline cleaning products are often used to remove oily residue from these processes.
A third type of hard surface cleaning is for cleaning industrial equipment, or any freight-carrying vehicle. Again, solvents, acids, or harsh alkaline products are used to remove dirt and grime, oily residue, and odors.